Showing papers in "Chemistry Letters in 2000"
TL;DR: Titania nanotubes with high photo-catalytic activity were synthesized in laurylamine hydrochloride / tetraisopropyl orthotitanate modified with acetylacetone system as mentioned in this paper.
Abstract: Titania nanotubes with high photo-catalytic activity were synthesized in laurylamine hydrochloride / tetraisopropyl orthotitanate modified with acetylacetone system. Formation of nanotubes was confirmed by transmission electron microscope images. These titania nanotubes had crystal structure of anatase and showed high photo-catalytic activity, i.e., the activity is about three times higher than Degussa-P-25 and higher than ST-01.
294 citations
TL;DR: The electrochemically stable and relatively high conductive room temperature molten salts (RTMS) have been obtained with the use of small ammonium cations such as methoxymethyltrimethylammonium and bis(trifluoromethylsulfonyl)imide as discussed by the authors.
Abstract: The electrochemically stable and relatively high conductive room temperature molten salts (RTMS) have been obtained with the use of small ammonium cations such as methoxymethyltrimethylammonium and bis(trifluoromethylsulfonyl)imide. The RTMS showed high conductivity (4.7 mS cm−1 at 25 °C) which is the highest value of all the ammonium based RTMS reported so far.
290 citations
TL;DR: Treatment of ZSM-5 in alkaline solution dramatically changes morphology of the ZSM, leading to the formation of mesopores whose size is almost uniform without destruction of microporous structure.
Abstract: Treatment of ZSM-5 in alkaline solution dramatically changes morphology of the ZSM-5, leading to the formation of mesopores whose size is almost uniform without destruction of microporous structure.
282 citations
TL;DR: The addition of bis(pinacolato)diboron [(Me4C2O2)B-B(O2C2Me4)] to α,β-unsaturated ketones, esters, nitriles, or terminal alkynes and coupling with allyl chlorides were carried out in DMF at room temperature in the presence of CuCl and AcOK as mentioned in this paper.
Abstract: The addition of bis(pinacolato)diboron [(Me4C2O2)B-B(O2C2Me4)] to α,β-unsaturated ketones, esters, nitriles, or terminal alkynes and the coupling with allyl chlorides were carried out in DMF at room temperature in the presence of CuCl and AcOK. The transmetalation from boron to copper generating a B–Cu species was proposed as the key step of the reactions.
235 citations
TL;DR: In this article, the authors achieved remarkable control of chirality within a long and stable columnar self-assembly of N,N′,N″-Tris((S)-3,7-dimethyl octyl)benzene-1,3,5-tricarboxamide in dilute solution by strong, unidirectional hydrogen bonding and cooperative side-chain interactions.
Abstract: Remarkable control of chirality within a long and stable columnar self-assembly of N,N′,N″-Tris((S)-3,7-dimethyloctyl)benzene-1,3,5-tricarboxamide in dilute solution is achieved by strong, unidirectional hydrogen bonding and cooperative side-chain interactions; IR and CD-spectroscopy have been used to elucidate these features.
140 citations
TL;DR: In this article, the effect of H2 on the selective reduction of NO by C3H8 over Ag/Al2O3 catalysts under lean-exhaust conditions was examined.
Abstract: We examine the effect of H2 on the selective reduction of NO by C3H8 over Ag/Al2O3 catalysts under lean-exhaust conditions. The NO reduction activity caused by C3H8 at low temperature (590-760 K) is greatly increased by adding H2 in the presence of excess oxygen and water vapor.
125 citations
124 citations
TL;DR: In this paper, a novel titanosilicate with the MWW topology was synthesized in the presence of boron and showed catalytic activity for the liquid phase oxidation reaction of cyclohexene after removal of the extra framework Ti species by an acid treatment.
Abstract: A novel titanosilicate with the MWW topology hydrothermally synthesized in the presence of boron shows catalytic activity for the liquid-phase oxidation reaction of cyclohexene after removal of the extraframework Ti species by an acid treatment.
109 citations
TL;DR: In this paper, all lanthanide(III) ions were found to catalyze dehydration of saccharides to 5-hydroxymethyl-2-furfural (HMF) in DMSO at 100 - 120 °C.
Abstract: All lanthanide(III) ions were found to catalyze dehydration of saccharides to 5-hydroxymethyl-2-furfural (HMF) in DMSO at 100 - 120 °C. Particularly, D-fructose was almost quantitatively converted to HMF without generating any byproducts. The results of the reaction with di- and trisaccharides indicated that the D-fructose moiety in the substrates was selectively converted to HMF.
105 citations
TL;DR: In this article, self-assembled nanocage 1 was found to promote the aerobic, aqueous oxidation of styrene and its derivatives with the aid of (en)Pd(NO3)2.
Abstract: Self-assembled nanocage 1 was found to promote the aerobic, aqueous oxidation of styrene and its derivatives with the aid of (en)Pd(NO3)2. Obviously, the reaction was promoted by a double catalysis system: i.e., cage 1 acted as a reverse phase-transfer catalyst, whereas (en)Pd2+ as an oxidation catalyst.
103 citations
TL;DR: In this paper, α,β-unsaturated ketones were synthesized by one-pot procedure from various ketones in good to excellent yields on treatment of their lithium enolates with N-tert-butyl phenylsulfinimidoyl chloride.
Abstract: α,β-Unsaturated ketones were synthesized by one-pot procedure from various ketones in good to excellent yields on treatment of their lithium enolates with N-tert-butyl phenylsulfinimidoyl chloride (1) under mild conditions.
TL;DR: The reduction of titanium dioxide (TiO2) by the hydrogen plasma treatment creates a new absorption band in the visible light region and is expected to create photocatalytic activity in this region as discussed by the authors.
Abstract: The reduction of titanium dioxide (TiO2) by the hydrogen plasma treatment creates a new absorption band in the visible light region and is expected to create photocatalytic activity in this region Anatase TiO2 powder, which has photocatalytic activity in the ultraviolet (UV) region, was treated using microwave and radio-frequency (RF) plasmas The TiO2 was reduced thus having an oxygen deficiency The RF-plasma-treated TiO2 absorbed visible light between 400 and 600 nm and showed a high activity in this region, as measured by the oxidative removal of nitric oxide from the gas phase The plasma-treated TiO2, which can be easily produced on a large scale, is expected to have a higher efficiency in utilizing solar energy than the raw material
TL;DR: In this article, C-promoted cobalt molybdenum bimetallic nitride (Co3Mo3N) was synthesized by nitridation of cobalt mixture with ammonia at 973K and was stable and more active for ammonia synthesis (15 mmol h−1g−1) at 673 K under 3.1 MPa (N2 + 3H2).
Abstract: Cs promoted cobalt molybdenum bimetallic nitride (Co3Mo3N) synthesized by nitridation of cobalt molybdate hydrate with ammonia at 973K was stable and more active for ammonia synthesis (15 mmol h−1g−1) at 673 K under 3.1 MPa (N2 + 3H2) than a doubly promoted iron catalyst.
TL;DR: In this article, a layered polymer/calcium carbonate composite films have been successfully obtained by alternate repetition of spin-coating of polysaccharides and thin film crystallization of CaCO3 in the presence of an acid polymer.
Abstract: Layered polymer/calcium carbonate (CaCO3) composite films have been successfully obtained by alternate repetition of spin-coating of polysaccharides and thin film crystallization of CaCO3 in the presence of an acid polymer. SEM images show layered structures consisting of brick of the inorganic crystal and mortar of the polymer.
TL;DR: In this paper, the secondary ammonium group in a rotaxane system with a crown ether was unusually lowered and N-acylation by acid anhydrides or chlorides proceeded slowly in the presence of excess tertiary amine.
Abstract: Acidity of a secondary ammonium group in a rotaxane system with a crown ether was unusually lowered. N-Acylation of the ammonium group by acid anhydrides or chlorides proceeded slowly in the presence of excess tertiary amine to give the N-acylated rotaxanes without salt structure.
TL;DR: In this paper, the synthesis of 1-alkenylboronic acid pinacol esters via the palladium-catalyzed cross-coupling reaction of triflates with bis(pinacolato)diboron [(Me4C2O2)B-B(O2C2 Me4)] was carried out in toluene at 50 °C in the presence of potassium phenoxide (1.5 equivalents).
Abstract: The synthesis of 1-alkenylboronic acid pinacol esters via the palladium-catalyzed cross-coupling reaction of 1-alkenyl halides or triflates with bis(pinacolato)diboron [(Me4C2O2)B-B(O2C2 Me4)] was carried out in toluene at 50 °C in the presence of potassium phenoxide (1.5 equivalents) and PdCl2(PPh3)2·2PPh3 (3 mol%).
TL;DR: In this article, bis(salicylaldiminato) zirconium complexes were synthesized and investigated as ethylene polymerization catalysts, and it was demonstrated that high molecular weight (Mw: 71.6 × 104) and super high activity (2096 kg-PE/mmol-Zr·h) were accomplished by changing the ligand structure.
Abstract: New bis(salicylaldiminato) zirconium complexes were synthesized and investigated as ethylene polymerization catalysts. As a result, we demonstrated that high molecular weight (Mw: 71.6 × 104) and super high activity (2096 kg-PE/mmol-Zr·h) were accomplished by changing the ligand structure.
TL;DR: A bis-maltolato zinc(II) (Zn(Mal)2) complex was revealed to be in an octahedral and a square pyramidal geometries in a unit cell.
Abstract: Zinc(II) complexes with a Zn(O4) coordination mode were found to have insulinomimetic activity. A bis-maltolato zinc(II) (Zn(Mal)2) complex was revealed to be in an octahedral and a square pyramidal geometries in a unit cell. Both Zn(Mal)2 (IC50 = 0.59 mM) and bis-2-hydroxypyridine-N-oxide zinc(II) (IC50 = 0.41 mM) complexes exhibited higher insulinomimetic activity than VOSO4(IC50 = 1.00 mM) and ZnSO4(IC50 = 0.81 mM) in terms of IC50 values, which show 50% inhibition concentration of the complex in the free fatty acids release from rat adipocytes.
TL;DR: A new class of hydrocarbon anions, pentaaryl-and pentamethylfullerene anions R5C60− (R = Ph, 4-BuC6H4, 4 -PhC6h4, Me) was found to be stable and soluble in water.
Abstract: A new class of hydrocarbon anions, pentaaryl- and pentamethylfullerene anions R5C60− (R = Ph, 4-BuC6H4, 4-PhC6H4, Me) was found to be stable and soluble in water. Atomic force microscopic observation and dynamic light scattering measurements indicated that the potassium salt Ph5C60K in water forms spherical aggregates with an averaged radius of about 17 nm.
TL;DR: In this article, two bis(pyrrolyl-2-aldiminato) titanium complexes were synthesized and their structures determined by X-ray analyses and they exhibited high ethylene polymerization activity using MAO or Ph3C+B−(C6F5)4/iBu3Al as a cocatalyst.
Abstract: Two new bis(pyrrolyl-2-aldiminato) titanium complexes were synthesized and their structures determined by X-ray analyses. These complexes displayed high ethylene polymerization activity using MAO or Ph3C+B−(C6F5)4/iBu3Al as a cocatalyst. One of the complexes exhibited very high ethylene polymerization activity (14100 kg-polymer·mol-Ti−1·h−1) with very high molecular weight (Mv: 260.1 × 104) using MAO as a cocatalyst.
TL;DR: In this article, irradiation of pulsed 1064-nm laser light to dodecanethiol-passivated gold nanoparticles in cyclohexane resulted in enormous growth of the particles.
Abstract: Irradiation of pulsed 1064-nm laser light to dodecanethiol-passivated gold nanoparticles in cyclohexane resulted in enormous growth of the particles The size increased up to ∼200 nanometers
TL;DR: In this paper, the performance of Ir catalysts for reduction of nitric oxide with carbon monoxide in the presence of SO2 and excess oxygen was investigated, and it was shown that the catalytic activity was scarcely influenced by 150 ppm SO2.
Abstract: Catalytic performance of Ir catalysts for reduction of nitric oxide with carbon monoxide in the presence of SO2 and excess oxygen was investigated. NO was selectively reduced with CO on Ir/silicalite in an oxidizing atmosphere containing 1% to 10% O2 in the temperature range of 300-500 °C. The catalytic activity was scarcely influenced by 150 ppm SO2.
TL;DR: In this paper, arylation of ethylene with benzene to produce styrene by addition of acetylacetone and O2 without any oxidizing agent like Cu salt was studied.
Abstract: Rh complexes were found to work as catalysts for oxidative arylation of ethylene with benzene to produce styrene by addition of acetylacetone and O2 without any oxidizing agent like Cu salt. Vinylacetate was not formed at all in spite of coexistence of acetic acid.
TL;DR: In this paper, a non-substituted 1,2-bis(3-thienyl)perfluorocyclopentene 1a was synthesized and its photochromic reactivity was compared with 1 2 -bis(2,5-dimethyl-3 thienyl), perfluorocylopenten 4a.
Abstract: Non-substituted 1,2-bis(3-thienyl)perfluorocyclopentene 1a was synthesized and its photochromic reactivity was compared with 1,2-bis(2,5-dimethyl-3-thienyl)perfluorocyclopentene 4a. Upon irradiation with ultraviolet light 1a easily decomposed and two kinds of by-products were produced in addition to the normal closed-ring isomer. The structures of the by-products were determined by X-ray crystallographic analysis.
TL;DR: In this article, the removal of hydrochloric acid utilizing magnesium-aluminum oxide (Mg-Al oxide), as prepared by the thermal decomposition of hydrotalcite (HT), was investigated.
Abstract: The removal of hydrochloric acid utilizing magnesium-aluminum oxide (Mg–Al oxide), as prepared by the thermal decomposition of hydrotalcite (HT), was investigated. Cl− in hydrochloric acid can be removed almost 100% by adding 1.75 times the stoichiometric quantity of Mg0.70Al0.20O at 60 °C for 1 h. Mg2+ and Al3+ in solution after the reaction were not recognized, because the solution was weakly alkaline.
TL;DR: In this article, a 2.5% solar energy conversion efficiency was achieved under AM 1.5 (99 mW cm−2) with a short-circuit photocurrent density (Jsc) of 7.44 mA cm −2, an open-circuits photovoltage (Voc) of 0.52 V, and a fill factor of 0.64.
Abstract: Mercurochrome showed efficient performance as an organic dye photosensitizer for a solar cell based on nanoporous ZnO thin film electrodes. A 2.5% solar energy conversion efficiency was accomplished under AM 1.5 (99 mW cm−2) with a short-circuit photocurrent density (Jsc) of 7.44 mA cm−2, an open-circuit photovoltage (Voc) of 0.52 V, and a fill factor of 0.64. A monochromatic incident photon-to-current efficiency (IPCE) reached 69% at 510 nm.
TL;DR: In this article, it was found that methyl-4,6-O-p-nitrobenzylidene-α-D-galactopyranoside (1) and methyl 4,6,O-b-n-dene-β-mannopyranoide (2) act as supergelators when they are enforcedly dissolved above their bp's in a sealed tube.
Abstract: It was found that methyl-4,6-O-p-nitrobenzylidene-α-D-galactopyranoside (1) and methyl-4,6-O-benzylidene-α-D-mannopyranoside (2), which are scarcely soluble in apolar solvents, act as “supergelators” when they are enforcedly dissolved above their bp’s in a sealed tube. The minimum gelator concentrations (Cmin) were 0.03–0.07% [g mL−1] which are one of the lowest concentrations achieved so far. The coupled study of TEM observation with partial solvent exchange established that the organogel stability is related to the superstructure in the fibril network constructed in specific solvents.
TL;DR: Bifunctional secondary ammonium salt bearing disulfide linkage at the center and bulky group at the both termini was mixed with dibenzo-24-crown-8 and crown ether entered the disulfides to afford corresponding [2] and [3]rotaxanes.
Abstract: Bifunctional secondary ammonium salt bearing disulfide linkage at the center and bulky group at the both termini was mixed with dibenzo-24-crown-8. During reversible cleavage of the disulfide linkage catalyzed by benzenethiol, crown ether entered the disulfide linkage to afford corresponding [2] and [3]rotaxanes.
TL;DR: In this article, a photochromic spin coupler was designed and synthesized, which showed photoswitching of intramolecular magnetic interaction by incorporating two nitronyl nitroxide into diarylethene photochromics.
Abstract: We have designed and synthesized 1,2-bis[6-(1-oxyl-3-oxide-4,4,5,5-tetramethylimidazolin-2-yl)-2-methylbenzo[b]thiophen-3-yl]hexafluorocyclopentene which shows photoswitching of intramolecular magnetic interaction by incorporating two nitronyl nitroxide into diarylethene photochromic spin coupler.
TL;DR: In this paper, a combinatorial library approach was used to find low molecular-weight organogelators composed of a bile acid-alkylamine salt; the gel phenomena were investigated by FT-IR spectroscopy, SEM, and X-ray crystallography.
Abstract: A combinatorial library approach enables us to find new low molecular-weight organogelators composed of a bile acid–alkylamine salt; the gel phenomena are investigated by FT-IR spectroscopy, SEM, and X-ray crystallography.